PromethiumPromethium.jpg

Promethium is named after the greek god Prometheus. It was predicted by Branner in 1902 and was confirmed in 1914 by Moseley. The symbol was originated from the pm in Prometheus.

Symbol: Pm
Atomic Number: 61
Atomic Mass: 145
Number of Protons: 61
Number of Electrons: 61
Number of Neutrons: 84
Boiling Point: ~3000C
Melting Point: 1042C
Density: 6.473 g/cm3
Promethium is not found in the Earth's crust. It can be found in spent nuclear fuel and in the Andromeda galaxy. It is used as a nuclear power battery. It glows a pale blue or light green due to its high radioactivity. Radioactivity is when an element is able to produce its own heat.

Sources
http://periodic.lanl.gov/elements/61.html
http://www.chemicalelements.com/elements/pm.html